In-wheel motor for electric automobiles

ABSTRACT

The present invention provides an in-wheel motor for an electric vehicle allowing a drive motor to be freely mounted onto a chassis irrespective of the shape, structure, and characteristics of the drive motor as well as allowing free selection of a reduction gear ratio without need to replace a drive motor. 
     An in-wheel motor for an electric vehicle includes a drive motor ( 1200 ), a reduction gear mechanism ( 1300 ), a wheel bearing, and a mechanical brake and serves as a drive apparatus for an electric vehicle. The drive motor ( 1200 ) includes a casing ( 1210 ) which houses a rotor ( 1240 ) and a stator ( 1220 ); the reduction gear mechanism ( 1300 ) is implemented by a planetary gear mechanism; a wheel bearing is fixedly attached to the outer circumference of an end portion of a housing ( 1411 ), which houses a wheel shaft ( 1410 ) coupled to an output element of the planetary gear mechanism; mounting blocks ( 800, 810 ) having engagement means are provided respectively at upper and lower outside portions of the casing ( 1210 ); and attachments are attached to the corresponding mounting blocks ( 800, 810 ) and joined to corresponding joint mechanisms ( 612, 712 ), which are movably coupled to a suspension mechanism.

TECHNICAL FIELD

The present invention relates to an in-wheel motor to be mounted in anelectric vehicle and, more particularly, to an in-wheel motor for anelectric vehicle devised to be freely mountable regardless of the shape,structure, and characteristics of a drive motor thereof.

BACKGROUND ART

Conventional in-wheel motors for electric vehicles consist of thosedescribed below.

FIG. 1 is a sectional view showing the structure of a conventionalin-wheel motor for an electric vehicle.

FIG. 1 shows an in-wheel motor that is configured such that the casingof a motor, which partially constitutes a drive mechanism, includesmounting means. In this electric vehicle, a drive mechanism 100 isintegrally incorporated into a driving wheel (in-wheel-motor type). Thedrive mechanism 100 is configured such that a drive motor 200, areduction gear mechanism 300, and a brake 400 are integrated into a unitmechanism. A tire 500 is mounted on the unit mechanism.

The drive motor 200 is a permanent-magnet-type AC motor. A casing 210 ofthe drive motor 200 is composed of an outer frame 211, an inner frame212, an end ring 213, and an end plate 214. The outer frame 211 iscylindrical and includes a bracket portion 211 a, which is locatedtowards the right in FIG. 1. The inner frame 212 is a cylindrical memberthat is concentrically disposed within the outer frame 211, and includesa bracket portion 212 a, which is located at the right end in FIG. 1.

The bracket portion 211 a and the bracket portion 212 a are joined viabolts, whereby the outer frame 211 and the inner frame 212 are joined.The end ring 213 and the end plate 214 are attached via bolts to theleft end face of the outer frame 211.

A stator 220, which includes a stator core 221 and a coil 222, ismounted on the inner circumferential surface of the outer frame 211. Acylindrical rotor 240 is rotatably mounted on the outer circumferentialsurface of the inner frame 212 via a motor bearing 230.

The rotor 240 includes a rotor core 241 and a permanent magnet 242. Arotary block 250 is attached to the rotor core 241 via bolts. Arevolution speed detector 260 is attached to the left-hand end of therotary block 250. A shaft 270 is serration-coupled to a right-handportion of the rotary block 250. AC current is supplied to the coil 222of the drive motor 200 through a cable 280. A revolution speed signalindicative of revolution speed detected by the revolution speed detector260 is output through a cable 281.

Support rings 290 and 291 formed in the outer frame 211 are fitted tocorresponding fulcrums of a suspension mechanism, whereby the drivemechanism 100 is mounted onto a chassis of the electric vehicle.

The reduction gear mechanism 300 is a planetary gear mechanism and isadapted to transmit rotation of the shaft 270 to a wheel shaft 410 afterreduction of speed. In this case, a carrier 301 of the reduction gearmechanism 300 is serration-coupled to the wheel shaft 410 so as totransmit torque to the wheel shaft 410 while being allowed to moveaxially.

A wheel shaft tube 411, through which the wheel shaft 410 extends, isfixedly attached to the bracket portions 211 a and 212 a. The reductiongear mechanism 300 is disposed in a space that is enclosed by the wheelshaft tube 411 and the bracket portion 212 a of the inner frame 212. Aring gear 302 of a planetary gear is formed on the inner surface of theinner frame 212. An end face of the shaft 270 and an end face of thewheel shaft 410 are pivoted by means of a pivot 412. The brake 400 is ahydraulic brake that uses a drum.

A wheel hub 420 is attached to the wheel shaft 410 via bolts. A brakedrum 430 and a disk wheel 505 of a wheel are attached to the wheel hub420 via bolts. A hub bearing 440, which serves as a wheel bearing, isinterposed between the wheel shaft tube 411 and the wheel hub 420. Aback plate of the brake 400 is fixedly attached to a flange portion ofthe wheel shaft tube 411. When hydraulic pressure increases as a resultof a brake pedal being stepped on, a wheel cylinder 401 causes brakeshoes 402 to be expanded, so that the brake shoes 402 come into contactwith the brake drum 430 for braking.

The tire 500 is mounted on a rim 510 of the disk wheel 505. In thethus-configured drive mechanism 100, when the motor 200 is activated tothereby rotate the rotor 240, rotation of the rotor 240 is transmittedto the rotary block 250 and the shaft 270 and is then speed-reduced atthe reduction gear mechanism 300. The speed-reduced rotation istransmitted to the wheel shaft 410. Thus, the tire 500 coupled to thewheel shaft 410 is rotated, whereby the electric vehicle moves.

FIG. 2 is a modified version of the drive mechanism 100 shown in FIG. 1.For application to a small-diameter tire 500, this modified drivemechanism employs a drive motor 200 having a long axial dimension and ashort radial dimension. Since the drive motor 200 has a short radialdimension, centrifugal force induced by the rotor 240 is small, and thusthe drive motor 200 can be a high-speed motor.

Therefore, the reduction gear mechanism 300 is designed to provide alarge reduction gear ratio; thus, the outside diameter of the reductiongear mechanism 300 is greater than the inside diameter of the stator220. Also in this embodiment, the ring gear 302 of the reduction gearmechanism 300 is formed on the inner surface of the inner frame 212.

Still another drive mechanism is disclosed in U.S. Pat. No. 5,087,229.This drive mechanism includes a drive motor, a reduction gearset, abrake, and a tire as well as a steering knuckle, a ball joint mechanism,etc. which are provided integrally with a motor wheel for supporting themotor wheel.

In FIG. 3, reference numeral 10 denotes a motor wheel; reference numeral12 denotes a steering knuckle; reference numeral 14 denotes a ball jointmechanism; reference numeral 16 denotes a motor wheel support element;reference numeral 18 denotes a vehicle shock tower; reference numeral 20denotes a frame member; reference numeral 22 denotes bolts; referencenumeral 24 denotes a mounting clamp; reference numeral 26 denotes aMcPherson assembly; reference numeral 28 denotes a plate; referencenumeral 30 denotes a nut; reference numeral 32 denotes a lower controlarm; reference numeral 34 denotes a sway bar; reference numeral 36denotes a ball joint mechanism; reference numeral 38 denotes a link;reference numeral 40 denotes a hub; reference numeral 42 denotes bolts;reference numeral 44 denotes a motor housing; reference numeral 46denotes bolts; reference numeral 48 denotes a housing of a planetaryreduction gearset assembly; reference numeral 49 denotes a gearset;reference numeral 50 denotes bolts; reference numeral 51 denotes asteering tie rod attached to the steering knuckle 12; reference numeral52 denotes a hub bearing element; reference numerals 53 and 54 denotebearings; reference numeral 58 denotes a disk rotor; reference numeral60 denotes a disk wheel; reference numeral 62 denotes lug nuts;reference numeral 64 denotes a tire; reference numeral 66 denotes avalve; reference numeral 68 denotes a caliper; reference numeral 72denotes pads; reference numeral 76 denotes cooling fins; referencenumeral 80 denotes a stator; reference numeral 82 denotes a coil;reference numeral 84 denotes lead-in conductors; reference numeral 86denotes a connector; reference numeral 88 denotes a cable; referencenumeral 90 denotes a driving shaft; reference numeral 91 denotes awasher; reference numeral 92 denotes a hub nut; reference numeral 93denotes a rotor; reference numeral 94 denotes a rotor; reference numeral95 denotes magnets; and reference numeral 96 denotes a rotationdetector.

DISCLOSURE OF THE INVENTION

In the conventional motors shown in FIGS. 1 and 2, the support rings 290and 291, which are used for mounting the motors onto respective chassis,are formed integrally with the casing 210. Required motorcharacteristics, such as low speed or high speed, or low torque or hightorque, depend on the size of a tire and vehicle characteristics. Thesize and shape of a motor vary depending on the required motorcharacteristics. Thus, the positions of the support rings 290 and 291,which are used for mounting the motor onto a chassis, vary accordinglyin relation to the casing 210 and to the tire 500.

Thus, when existing in-wheel motors designed for certain vehicles are tobe applied to another vehicle, an applicable in-wheel motor is limitedto that having a specific mounting section; i.e., a mounting sectionthat satisfies a specific positional relation between the mountingsection and a wheel. Also, when an in-wheel motor of a certain tire isto be applied to a tire of a different diameter or when a certainin-wheel motor is to be replaced with an in-wheel motor of differentmotor characteristics, the desired application or replacement may beinfeasible if the positions of the support rings 290 and 291 areincompatible. Further, as is apparent from the above-describedconventional motors, the axial length of a motor casing changesdepending on motor characteristics, and the position of the mountingsection changes accordingly.

Therefore, an in-wheel motor has been selected according to the positionof a mounting section, not according to motor characteristics, therebynarrowing the range of selection and thus raising difficulty in designand affecting convenience of use.

When the revolution speed of a wheel and a driving torque are to bechanged without changing motor output, reduction gear ratio must bechanged. In this case, a conventional motor does not allow replacementof a reduction gear only, but requires replacement of an entire motor.

An object of the present invention is to solve the above-mentionedproblems in a conventional in-wheel motor and to provide an in-wheelmotor for an electric vehicle allowing a drive motor to be freelymounted onto a chassis irrespective of the shape, structure, andcharacteristics of the drive motor as well as allowing free selection ofa reduction gear ratio without need to replace a drive motor.

To achieve the above object, the present invention provides thefollowing in-wheel motors for an electric vehicle.

[1] An in-wheel motor for an electric vehicle comprises a drive motor, areduction gear mechanism, a wheel bearing, and a mechanical brake andserves as a drive apparatus for an electric vehicle. The in-wheel motoris characterized in that the drive motor includes a casing which housesa rotor and a stator; the reduction gear mechanism comprises a planetarygear mechanism; a wheel bearing is fixedly attached to the outercircumference of an end portion of a housing, which houses a wheel shaftcoupled to an output element of the planetary gear mechanism; mountingblocks having engagement means are provided respectively at upper andlower outside portions of the casing; and attachments are attached tothe corresponding mounting blocks and joined to corresponding jointmechanisms, which are movably coupled to a suspension mechanism.

[2] In the in-wheel motor for an electric vehicle as described above in[1], the attachments are characterized in that a line connecting thecenters of rotation of the joint mechanisms, which are fixedly attachedto the corresponding attachments, forms a king pin angle with respect tothe center axis of a wheel.

[3] In the in-wheel motor for an electric vehicle as described above in[1], a steering tie rod is coupled to either of the attachments.

[4] An in-wheel motor for an electric vehicle comprises a drive motor, areduction gear mechanism, a wheel bearing, and a mechanical brake andserves as a drive apparatus for an electric vehicle. The in-wheel motoris characterized in that the drive motor includes a casing which housesa rotor and a stator; the reduction gear mechanism comprises a planetarygear mechanism; a wheel bearing is fixedly attached to the outercircumference of an end portion of a housing, which houses a wheel shaftcoupled to an output element of the planetary gear mechanism; themechanical brake is a drum brake or a disk brake; the planetary gearmechanism is housed within the housing, and an input shaft of theplanetary gear mechanism is spline-coupled to a rotary shaft of thedrive motor; and the housing is attached to the casing via bolts.

[5] In the in-wheel motor for an electric vehicle as described above in[4], the planetary gear mechanism is configured such that a partition isprovided within a gear chamber for controlling stirring of lubricationoil.

[6] In the in-wheel motor for an electric vehicle as described above in[1] or [4], a rotational-position detector is disposed on the side ofthe rotor opposite the output side of the rotor, and therotational-position detector is a resolver.

[7] In the in-wheel motor for an electric vehicle as described above in[1] or [4], the drive motor is a 6-phase synchronous AC motor.

[8] In the in-wheel motor for an electric vehicle as described above in[1] or [4], coil ends of an armature, which partially constitutes thestator, are mechanically compressed from axially opposite sides.

[9] In the in-wheel motor for an electric vehicle as described above in[1] or [4], the joint mechanism is a ball joint mechanism or a sphericaljoint mechanism.

As mentioned above, the configuration of the present invention ischaracterized in that means for mounting an in-wheel motor comprises themounting blocks provided on the casing of the in-wheel motor; the jointmechanisms, which are movably coupled to a suspension mechanism; and theattachments, which are attached to the corresponding mounting blocks andjoined to the corresponding joint mechanisms.

The configuration of the present invention is characterized in thatmeans for attaching the above-mentioned attachments to the mountingblocks is in common among various attachments and that otherspecifications of the attachments are modified as appropriate so as tobe compatible with various applications.

The configuration of the present invention is characterized in that theabove-mentioned mounting blocks are provided respectively at an upperportion and a lower portion of the casing and that the above-mentionedattachments are provided in correspondence with the mounting blocks.

The configuration of the present invention is characterized in thatmeans for mounting an in-wheel motor comprises a mounting block providedon an upper portion of the casing; a support portion of an upper arm,which partially constitutes the attachment, the support portion beingcoupled to a joint mechanism; a mounting block provided on a lowerportion of the casing; and a support portion of a lower arm, whichpartially constitutes the attachment, the support portion being coupledto a joint mechanism.

The configuration of the present invention is characterized in that thecoupling surface of each mounting block and the coupling surface of acoupling portion of each arm, which partially constitutes theattachment, can abut each other at any mounting angle.

The configuration of the present invention is characterized in that theplanetary gear mechanism is housed within the housing while a ring gearis provided on the inner surface of the housing; the input shaft of theplanetary gear mechanism is spline-coupled to the rotary shaft of thedrive motor; and the housing is attached to the casing via bolts.

The configuration of the present invention is characterized in that thepartition for controlling stirring of lubrication oil is providedbetween the end face of the planetary gear mechanism and a bracketportion of the motor casing.

According to the present invention, only the upper and lower mountingblocks are formed on an in-wheel motor body such that coupling surfacesof the blocks are common among different types of vehicles. Whilecoupling specifications are common among various upper arms and amongvarious lower arms, other specifications of the upper and lower arms aremodified according to, for example, mounting length and mounting height,whereby the mounting blocks are coupled to a suspension mechanism bymeans of the upper and lower arms. A steering tie rod is coupled toeither the upper arm or the lower arm.

Conventional motor mounting means is integral with a motor casing; thus,mounting position, mounting height, etc. are fixed. Therefore,replacement with a drive motor of a different type is difficult unlessthe replacing drive motor has the same mounting dimensions as those of adrive motor to be replaced. By contrast, according to the presentinvention, the attachment and the casing are discrete members.Therefore, even when a replacing drive motor is of a different type, thereplacing drive motor can be mounted by means of changing attachments.

Through change in the gear ratio of the planetary gear mechanism of thereduction gear mechanism, revolution speed of a wheel and driving torquecan be changed without need to replace a drive motor.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a longitudinal sectional view of a conventional in-wheel motorfor an electric vehicle;

FIG. 2 is a longitudinal sectional view of another conventional in-wheelmotor for an electric vehicle;

FIG. 3 is a longitudinal sectional view of still another conventionalin-wheel motor for an electric vehicle;

FIG. 4 is a schematic view showing means for mounting an in-wheel motorin a drive system of an electric vehicle to which the present inventionis applied; and

FIG. 5 is a longitudinal sectional view of an in-wheel motor for anelectric vehicle of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Modes for carrying out the present invention will next be described withreference to the drawings.

Embodiments of the present invention will next be described withreference to the following drawings.

FIG. 4 exemplifies an in-wheel motor of the present invention and meansfor mounting the in-wheel motor while other structural features areomitted. FIG. 5 is a longitudinal sectional view of the in-wheel motoraccording to the present invention.

First, the in-wheel motor of the present invention, particularly theinner structure thereof, will be described with reference to FIGS. 4 and5.

A drive motor 1200 in a drive mechanism 1100 is a permanent-magnet-typeAC motor, particularly a 6-phase synchronous AC motor. A casing 1210 ofthe drive motor 1200 includes an outer frame 1211, an end ring 1213, andan end plate 1214. The outer frame 1211 is cylindrical and includes abracket portion 1211 a, which is located at the right-hand side thereofin FIG. 5. A stator 1220, which is composed of a stator core 1221 and acoil 1222, is mounted on the inner circumferential surface of the outerframe 1211. In order to reduce idle space, the number of poles of thecoil 1222 is six, and the coil 1222 uses thin wires. Also, in order toreduce the axial length of the drive motor 1200, coil ends aremechanically compressed from opposite sides. Reference letters A and Bdenote attachments.

A rotor 1240 includes a rotor core 1241 and a permanent magnet 1242.Rotary shaft blocks 1251 and 1252, which constitute a rotary shaft ofthe drive motor 1200, are attached to the rotor core 1241 via bolts. Ashaft portion 1251 a of the rotary shaft block 1251 is supportedrotatably by means of a motor bearing 1231, which is fixedly attached tothe end ring 1213. A revolution speed detector 1260 such as a resolveris attached to the left-hand end of the shaft portion 1251 a. A shaftportion 1252 a of the rotary shaft block 1252 is supported rotatably bymeans of a motor bearing 1232, which is fixedly attached to the bracketportion 1211 a of the outer frame 1211. Serrations are formed on theinner surface of the shaft portion 1252 a, so that the shaft portion1252 a is spline-coupled to an input shaft 1270 of a reduction gearmechanism 1300.

A housing 1411 houses the reduction gear mechanism 1300. A wheelbearing; i.e., a hub bearing 1440, is fixedly attached to the outercircumference of a wheel shaft tube portion 1411 a of the housing 1411.The housing 1411 is attached via bolts 1215 to the bracket portion 1211a of the outer frame 1211 of the drive motor 1200.

AC current is supplied to the coil 1222 of the drive motor 1200 througha cable 1280. A revolution speed signal indicative of revolution speeddetected by the revolution speed detector 1260 is output via a cable1281.

The reduction gear mechanism 1300 is implemented by means of a planetarygear mechanism and adapted to reduce the revolution speed of the inputshaft 1270 to thereby transmit the reduced revolution speed to a wheelshaft 1410. A partition 1302 is provided within a gear chamber forcontrolling stirring of lubrication oil. The planetary gear mechanismmay be of a single stage or a plurality of stages.

In this case, a ring gear 1303 of the planetary gear mechanism isprovided on the inner surface of the housing 1411. A carrier 1301 isspline-coupled to the wheel shaft 1410 so as to transmit torque to thewheel shaft 1410 while being allowed to move axially. The wheel shaft1410 is disposed within the wheel shaft tube portion 1411 a of thehousing 1411.

An end face of the input shaft 1270 and an end face of the wheel shaft1410 are pivoted by means of a pivot 1412. A brake 1400 is a mechanicaldrum brake. A back plate 1403 of the brake 1400 is fixedly attached toan end face of the housing 1411. A wheel hub 1420 is attached to thewheel shaft 1410 via bolts. A brake drum 1430 and a disk wheel 1505 of awheel are attached to the wheel hub 1420 via bolts.

A hub bearing 1440 is interposed between the wheel shaft tube portion1411 a and the wheel hub 1420. The brake 1400 operates in the followingmanner. As hydraulic pressure increases as a result of a brake pedalbeing stepped on, a wheel cylinder 1401 causes brake shoes 1402 to beexpanded, so that the brake shoes 1402 come into contact with the brakedrum 1430 for braking.

A tire 1500 is mounted on a rim 1510 of the disk wheel 1505.

In the drive mechanism 1100, when the drive motor 1200 is activated tothereby rotate the rotor 1240, rotation of the rotor 1240 is transmittedto the rotary shaft block 1252 and the input shaft 1270 of the reductiongear mechanism 1300 and is then speed-reduced at the reduction gearmechanism 1300. The speed-reduced rotation is transmitted to the wheelshaft 1410. Thus, the tire 1500 is rotated via the wheel hub 1420coupled to the wheel shaft 1410, whereby the electric vehicle moves.

Next, an embodiment of means for mounting the in-wheel motor of thepresent invention will be described with reference to FIG. 4.

An upper mounting block 800 and a lower mounting block 810 areintegrally formed on the casing 1210 of the drive motor at an upperportion of the casing 1210 and at a lower portion of the casing 1210,respectively. The upper mounting block 800 is formed on an upper portionof the casing 1210 and assumes a substantially platelike shape. Couplingsurfaces 801 a and 801 b are formed on the corresponding end faces ofthe substantially platelike mounting block 800, the end faces extendingalong the longitudinal direction of the casing 1210. A plurality offemale screw portions (not shown) are formed on each of the couplingsurfaces 801 a and 801 b.

The lower mounting block 810 is formed on a lower portion of the casing1210 and assumes a substantially platelike shape. Coupling surfaces 811a and 811 b are formed on the corresponding end faces of thesubstantially platelike mounting block 810, the end faces extendingalong the longitudinal direction of the casing 1210. A plurality offemale screw portions are formed on each of the coupling surfaces 811 aand 811 b. That is, the upper mounting block 800 has the couplingsurfaces 801 a and 801 b, to which an upper arm 600 is attached, and thelower mounting block 810 has the coupling surfaces 811 a and 811 b, towhich a lower arm 700 is attached.

The shape of the coupling surfaces, the angle of the coupling surfaceswith respect to a horizontal plane and the like can be designedarbitrarily. The angles of the coupling surfaces determine the angles ofcoupling portions 601 a and 601 b of the upper arm 600, which abut theupper mounting block 800, and the angles of coupling portions 701 a and701 b of the lower arm 700, which abut the lower mounting block 810.Reference numerals 604 a, 604 b, 704 a, and 704 b denote locking screwsto be engaged with female screws formed in the coupling surfaces.

The upper arm 600 includes a support portion 603, arm portions 602 a and602 b, and the coupling portions 601 a and 601 b.

As mentioned above, the coupling portions 601 a and 601 b are formed soas to abut the coupling surfaces 801 a and 801 b, respectively, of theupper mounting block 800. The arm portions 602 a and 602 b are shaped soas to extend between the support portion 603 and the coupling portions601 a and 601 b. The shape of the arm portions 602 a and 602 b must bedetermined so as to exhibit sufficient strength and rigidity to endurethe weight of the vehicle and an impact force transmitted from the wheelto the support portion 603 and a support portion 703, which will bedescribed later.

A ball joint mechanism 612 or a spherical joint mechanism is coupled tothe support portion 603.

The ball joint mechanism 612 assumes a known structure. A taper shaft609 of the ball joint mechanism 612 is inserted into a through-hole 608formed in the support portion 603 and locked by means of a nut 610. Anupper arm of an unillustrated suspension mechanism is attached to asuspension attachment portion 605 of the ball joint mechanism 612.

A coupling 613, to which a steering tie rod is coupled, is provided onthe support portion 603 and located away from the through-hole 608. Thetie rod coupling 613 may be provided on the lower arm 700, which will bedescribed later.

As shown in FIG. 5, the shaft 609 is inclined at a predetermined anglewith respect to the horizontal plane of the support portion 603.

A line that connects the center of rotation of the shaft 609 of the balljoint mechanism 612 and the center of rotation of a shaft 709 of a balljoint mechanism 712, which will be described later, forms a king pinangle θ with respect to the center axis of a wheel. The king pin angle θis determined in view of steering stability of a vehicle and the like.

The lower arm 700 includes a support portion 703, arm portions 702 a and702 b, and the coupling portions 701 a and 701 b. The support portion703 assumes a flat-plate shape and is disposed horizontally while beinglocated away from the bottom surface of the lower mounting block 810 ofthe casing 1210.

As mentioned above, the coupling portions 701 a and 701 b are formed soas to abut the coupling surfaces 811 a and 811 b, respectively, of thelower mounting block 810. The arm portions 702 a and 702 b are shaped soas to extend between the support portion 703 and the coupling portions701 a and 701 b. As in the case of the arm portions 602 a and 602 b ofthe upper arm 600, the shape of the arm portions 702 a and 702 b must bedetermined so as to exhibit sufficient strength and rigidity to endurethe weight of the vehicle and an impact force transmitted from the wheelto the support portion 703.

The ball joint mechanism 712 assumes a known structure. A taper shaft709 of the ball joint mechanism 712 is inserted into a through-hole 708formed in the support portion 703 and locked by means of a nut 710. Asuspension attachment portion 705 of the ball joint mechanism 712 isattached to a lower arm of a suspension mechanism (not shown). As shownin FIG. 5, the shaft 709 is inclined at a predetermined angle withrespect to the horizontal plane of the support portion 703.

The shaft 709 of the ball joint mechanism 712 is provided such that theaxis thereof is aligned with the axis of the shaft 609 of the ball jointmechanism 612. As mentioned above, this alignment feature is employed inview of steering stability of a vehicle and the like.

The present invention is characterized in that:

(1) the upper mounting block 800 having the coupling surfaces 801 a and801 b which are common among different types of vehicles and the lowermounting block 810 having the coupling surfaces 811 a and 811 b whichare common among different types of vehicles are formed on the casing1210 of the drive motor;

(2) the upper arm 600—which includes the coupling portions 601 a and 601b which abut the coupling surfaces 801 a and 801 b which are commonamong different types of vehicles, the support portion 603 which iscoupled to a suspension mechanism, and the arm portions 602 a and 602 bwhich extend between the support portion 603 and the coupling portions601 a and 601 b—is fixedly attached to the coupling surfaces 801 a and801 b of the upper mounting block 800 by use of the locking screws 604 aand 604 b or the like; and

(3) the lower arm 700—which includes the coupling portions 701 a and 701b which abut the coupling surfaces 811 a and 811 b which are commonamong different types of vehicles, the support portion 703 which iscoupled to the suspension mechanism, and the arm portions 702 a and 702b which extend between the support portion 703 and the coupling portions701 a and 701 b—is fixedly attached to the coupling surfaces 811 a and811 b of the lower mounting block 810 by use of the locking screws 704 aand 704 b or the like.

Also, the present invention is characterized in that, in the in-wheelmotor described above in (1), (2), and (3), the support portions 603 and703 of the arms 600 and 700 are coupled to the suspension mechanism viathe ball joint mechanisms 612 and 712 or respective spherical jointmechanisms.

Further, the present invention is characterized in that the ring gear1303 of the reduction gear mechanism 1300, which reduces the revolutionspeed of the drive motor and transmits the reduced revolution speed tothe wheel, is formed on the inner surface of the housing 1411, which isa member separate from the motor casing 1210; the input shaft 1270 ofthe reduction gear mechanism 1300 is spline-coupled to the shaft portion1252 a of the drive motor; and the housing 1411 is removably attached tothe casing 1210 via bolts.

The present invention is not limited to the above-described embodiments.Numerous modifications and variations of the present invention arepossible in light of the spirit of the present invention, and they arenot excluded from the scope of the present invention.

As described above, the present invention yields the following effects.

(A) Only the upper and lower mounting blocks are formed on an in-wheelmotor body such that coupling surfaces of the blocks are common amongdifferent types of vehicles. A plurality of types of upper and lowerarms are prepared such that, while coupling specifications are commonamong the upper arms and among the lower arms, other specifications ofthe upper and lower arms are modified according to, for example,mounting height. An upper arm and a lower arm are selected from theprepared upper and lower arms as appropriate for individualapplications. The upper and lower mounting blocks are coupled to asuspension mechanism by means of the thus-selected upper and lower arms.

Conventional motor mounting means is integral with a motor casing; thus,mounting position, mounting height, etc. are fixed. Therefore,replacement with a drive motor of a different type is difficult unlessthe replacing drive motor has the same mounting dimensions as those of adrive motor to be replaced. By contrast, according to the presentinvention, the attachment, which serves as motor mounting means, and thecasing are discrete members. Therefore, even when a replacing drivemotor is of a different type, the replacing drive motor can be mountedby means of changing attachments.

(B) The present invention allows a wheel drive section including a speedreduction mechanism to be separated from a drive motor. Therefore,through change in the gear ratio of a reduction gear apparatus, therevolution speed of a wheel and driving torque can be changed, wherebytire diameter can be selected freely without need to replace a drivemotor.

INDUSTRIAL APPLICABILITY

The in-wheel motor of the present invention can cope with changes inspecifications and performance of a vehicle through replacement of unitsand is favorably used in an electric vehicle.

1. An in-wheel motor for an electric vehicle comprising a drive motor, areduction gear mechanism, a wheel bearing, and a mechanical brake andserving as a drive apparatus for an electric vehicle, said in-wheelmotor being characterized in that said drive motor includes a casingwhich houses a rotor and a stator; said reduction gear mechanismcomprises a planetary gear mechanism; a wheel bearing is fixedlyattached to an outer circumference of an end portion of a housing, whichhouses a wheel shaft coupled to an output element of said planetary gearmechanism; said housing houses said planetary gear mechanism therein andis attached to said casing via bolts; mounting blocks having engagementmeans are provided respectively at upper and lower outside portions ofsaid casing; and attachments are attached to said corresponding mountingblocks and joined to corresponding joint mechanisms, which are movablycoupled to a suspension mechanism.
 2. An in-wheel motor for an electricvehicle as described in claim 1, wherein said attachments arecharacterized in that a line connecting centers of rotation of saidjoint mechanisms, which are fixedly attached to said correspondingattachments, forms a king pin angle with respect to a center axis of awheel.
 3. An in-wheel motor for an electric vehicle as described inclaim 1, wherein a steering tie rod is coupled to either of saidattachments.
 4. An in-wheel motor for an electric vehicle as describedin claim 1, wherein a rotational-position detector is disposed on a sideof said rotor opposite an output side of said rotor, and saidrotational-position detector is a resolver.
 5. An in-wheel motor for anelectric vehicle as described in claim 1, wherein said drive motor is a6-phase synchronous AC motor.
 6. An in-wheel motor for an electricvehicle as described in claim 1, wherein coil ends of an armature, whichpartially constitutes said stator, are mechanically compressed fromaxially opposite sides.
 7. An in-wheel motor for an electric vehicle asdescribed in claim 1, wherein said joint mechanism is a ball jointmechanism or a spherical joint mechanism.
 8. An in-wheel motor for anelectric vehicle comprising a drive motor, a reduction gear mechanism, awheel bearing, and a mechanical brake and serving as a drive apparatusfor an electric vehicle, said in-wheel motor being characterized in thatsaid drive motor includes a casing which houses a rotor and a stator;said reduction gear mechanism comprises a planetary gear mechanism; awheel bearing is fixedly attached to an outer circumference of an endportion of a housing, which houses a wheel shaft coupled to an outputelement of said planetary gear mechanism; said mechanical brake is adrum brake or a disk brake; said planetary gear mechanism is housedwithin said housing, and an input shaft of said planetary gear mechanismis spline-coupled to a rotary shaft of said drive motor; and saidhousing is attached to said casing via bolts.
 9. An in-wheel motor foran electric vehicle as described in claim 8, wherein said planetary gearmechanism is configured such that a partition is provided within a gearchamber for controlling stirring of lubrication oil.
 10. An in-wheelmotor for an electric vehicle as described in claim 8, wherein arotational-position detector is disposed on a side of said rotoropposite an output side of said rotor, and said rotational-positiondetector is a resolver.
 11. An in-wheel motor for an electric vehicle asdescribed in claim 8, wherein said drive motor is a 6-phase synchronousAC motor.
 12. An in-wheel motor for an electric vehicle as described inclaims 8, wherein coil ends of an armature, which partial constitutessaid stator, are mechanically compressed from axially opposite sides.